BOULDER, Colo. - The win brought as much relief as jubilation for Colorado.

The loss brought more anger than heartbreak for CSU.

Like a couple of brothers going at it in the backyard before dinner, the Buffs and Rams looked like they could've kept playing forever Saturday evening. Naturally, the team that scored last won. This time, it was the Buffaloes who sneaked away on top, 31-28.

"A classic for college football," Buffs coach Gary Barnett called it after watching his team overcome an 11-point deficit over the final 13½ minutes.

Mason Crosby kicked a 47-yard field goal with 4 seconds left for the game-winner -- the last of 20 points the rivals put up over the frantic, final 2:32.

When it was over, CU fans flooded the field and a record Folsom Field crowd of 54,972 -- save the small cloister of Rams fans in the corner -- celebrated a win in one of the most underrated rivalries in the country.

Tight end Quinn Sypniewski left the field carrying the silver trophy awarded to the winner each year. Did he know what the trophy was called?

"Ours," Sypniewski said, as he worked his way toward a happy locker room.

Many in Boulder condescendingly view CSU as the little brother in this Rocky Mountain rivalry.

"But if we're such an underdog, why are they coming onto the field?" CSU quarterback Justin Holland asked.

Indeed, CSU has proven itself very much a challenge for Colorado. But CU has won four straight and in the last two games, the difference has been three points -- one field goal from the leg of arguably the nation's best kicker.

Crosby's game-winner came on his 21st birthday and added to a 48-yarder that cleared the crossbar by plenty with 2:32 left to tie the game at 21.

"He's got a hell of a leg and he's hurt us the last couple years," Holland said.

Two plays after Crosby tied it, Holland threw his third interception over a 15-minute span, a forced floater that Gerett Burl caught and returned to the CSU 23. On the next snap, Hugh Charles ran untouched for a touchdown, his second score of the fourth quarter, to make it 28-21 with 1:30 left.

Holland came back, though, and marched the Rams 80 yards in 54 seconds, capping it with a 9-yard pass to Kory Sperry to make it 28-27. CSU coach Sonny Lubick thought about going for 2, "but they talked me out of it," he said of his assistants.

After the extra point, CSU squibbed the kickoff, but Colorado returned it to the 40. Joel Klatt (22-for-33, 283 yards) hit Patrick Williams to get the ball into Rams territory and after an eight-yard gain, Crosby came on for the win.

Crosby, whose range is estimated at around 70 yards, said he didn't even know how long the final attempt was when he walked onto the field.

"That whole last kick was probably mental," he said. "Once I hit the ball, I just really didn't think about it. I had been preparing on the sideline."

It marked yet another tough loss in this series for the Rams. This one was made worse because CSU dominated through most of three quarters, taking a 21-10 lead and leaving the Buffs looking helpless.

"Nobody's heartbroken in there," Holland said of the CSU locker room. "We're more mad than anything."

"We're a damned good football team and I'm proud of my club," Lubick said.

The senior quarterback (28-for-43 for 281 yards) shouldered much of the blame last season when, trailing by three with the clock ticking down, he and Lubick mismanaged the clock and failed in two hurried attempts to gain one yard for what would have been the winning touchdown.

This year, Holland stood outside the locker room and answered questions for a good 20 minutes, not shirking from the three interceptions he threw down the stretch. Had any of them been avoided, the outcome likely would have been different.

"Those were mistakes I'm expected to get control of," Holland said. "I spent a lot of time in the offseason working to try to eliminate those mistakes. I took too many risks. I've got to throw the ball out of bounds. I can't try to make things happen when they're not there."

Holland will regret those three interceptions, but his drive for the tying touchdown was impressive -- he went 6-for-7 for 80 yards and the score.

Only this time, the Rams wish they'd taken more time off the clock instead of less.

Colorado, meanwhile, breathes a big sigh of relief after an impressive comeback.

Many in Boulder view this as a no-win situation for the Buffs, who play in a bigger conference (Big 12 vs. Mountain West) against a team that often comes in feeling it has nothing to lose.

But it was hard to feel like the Buffs didn't win something after this furious finish.

"I hate to use the word `surreal,' but it was just a great moment," said Sypniewski, a senior. "I can't even put it into words. Just being able to hold that trophy up my last year here is great."